<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>基本的选择器</title>
  <link rel="stylesheet" href="../css.css">

</head>
<body>

  <div class="box">
     test-box
  </div>

  <div class="box">
     test-box
  </div>

  <div id="box1">
    test-box
  </div>

 <h1>红色标题</h1>
</body>
</html>